Apparatus and method for preventing free flow in an infusion line

ABSTRACT

An apparatus and method for preventing free flow through an infusion set utilizes an occluder disposed within the infusion set to selectively prevent flow therethrough. The occluder may be responsive to a pressure differential within the infusion set or may respond to compression of the infusion set. When a pair of occluders are used in sequence, an in-line pump may be formed.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an apparatus and method forpreventing free flow during enteral or parenteral administrationsolutions through an infusion line. More particularly, the presentinvention relates to an occluder/valve and method of use for infusionsets and the like, wherein the occluder/valve prevents undesirablefree-flow of solution through the infusion set while allowing controlledflow through the infusion set.

[0003] 2. State of the Art

[0004] The use of infusion sets to administer solutions to patients iswell known in the medical arts. Infusion sets are used for both enteraland parenteral applications. Enteral feeding pumps are used to providepatients with nutrition and medication when they are unable, for avariety of reasons, to eat normally. Parenteral (intravenous) solutionsare provided to patients to ensure adequate hydration and to provideneeded nutrients, minerals and medication. Often, the infusion set isplaced in a free standing arrangement in which gravity forces thesolution into the patient. The rate at which the solution enters thepatient can be roughly controlled by various clamps, such as rollerclamps, which are currently available on the market.

[0005] In many applications, it is necessary to precisely control theamount of solution which enters the patient. When this is the case, aregulating device, such as an enteral feeding pump, is placed along theinfusion set to control the rate at which the solution is fed to thepatient. In applications where a pump, etc., is used, the clamps used toregulate flow are typically opened to their fullest extent to preventthe clamp from interfering with the proper functioning of the pump. Theclamp is opened with the expectation that the enteral feeding pump willcontrol fluid flow through the infusion set. However, emergencies orother distractions may prevent the medical personnel from properlyloading the infusion set in the enteral feeding pump.

[0006] When the infusion set is not properly loaded in the pump and theclamp has been opened, a situation known as free-flow often develops.The force of gravity causes the solution to flow freely into the patientunchecked by the pump or other regulating device. Under a free-flowcondition, an amount of solution many times the desired dose can besupplied to the patient within a relatively short time period. This canbe particularly dangerous if the solution contains potent medicines andthe patient's body is not physically strong enough to adjust to thelarge inflow of solution.

[0007] Numerous devices have been developed in an attempt to preventfree flow conditions. Such devices, however, typically add significantlyto the overall cost of the infusion set and some provide only marginalprotection against free flow.

[0008] Thus, there is a need for a device that prevents a free-flowcondition while allowing controlled flow through the infusion set. Thereis also a need for such a device which prevents free-flow if an infusionset is not properly mounted in a pump or other regulating means.

SUMMARY OF THE INVENTION

[0009] It is an object of the present invention to provide an apparatusand method for occluding infusion sets to prevent an accidentalfree-flow condition.

[0010] It is another object of the present invention to provide anoccluder which is simple to make and use.

[0011] It is another object of the present invention to provide such anoccluder which is inexpensive and thus disposable.

[0012] It is still another object of the present invention to provide anoccluder which occludes fluid flow through the infusion set unless theinfusion set is properly loaded in a flow control mechanism such as anenteral feeding pump.

[0013] It is still yet another object of the present invention toprovide such an occluder which allows for a simple manual override ofthe occluding function.

[0014] It is still yet another aspect of the invention to provide anoccluder which functions as a valve to effectively control fluid flowthrough a flexible conduit.

[0015] The above and other objects of the invention are realized in anapparatus and method for preventing free flow in an infusion set. Inaccordance with one aspect of the invention, an occluder is disposedwithin the infusion set. The occluder is configured to prevent free flowof fluids in the infusion set past the occluder. The occluder is alsoconfigured, however, selectively to allow solutions to pass by theoccluder which are pumped by an enteral feeding pump and the like.

[0016] In accordance with one embodiment of the invention, the occluderis formed by a stop placed in the tubing of the infusion set. The stoplimits flow around and/or through the stop when the solution is subjectto flow due to gravity. However, when greater pressures are placed onthe solution, such as those produced by a pump, the solution is able toflow around and/or through the stop, thereby delivering the solution tothe patient.

[0017] In accordance with another embodiment of the present invention,an occluding valve is disposed in the infusion set. The valve preventsfree flow through the infusion set due to gravity, while allowingcontrolled flow of solution through the infusion set.

[0018] In accordance with another aspect of the invention, the occluderis configured to stop fluid flow until the infusion set has beenproperly loaded into a control mechanism such as a pump. Once properlyplaced, the interaction between the occluder and the infusion seteffectively opens the infusion set to allow solution to flowtherethrough.

[0019] In accordance with still another aspect of the present invention,the occluder can be formed integrally with the infusion set or can beformed of independent piece(s)which are then placed in the infusion setto selectively occlude the flow of solution therethrough.

[0020] In accordance with still yet another aspect of the invention, theoccluder can function as a valve to selectively allow fluid flowtherethrough. In one embodiment, a pair of occluders and infusion linecan be used in conjunction with a piston or other force applicator toform a linear peristaltic pump which delivers predetermined amounts offluid to a patient.

[0021] In accordance with still yet another aspect of the presentinvention, the occluder and infusion line can be formed to nest in andbe opened by a conventional fluid flow pump.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other objects, features and advantages of theinvention will become apparent from a consideration of the followingdetailed description presented in connection with the accompanyingdrawings in which:

[0023]FIG. 1 shows an perspective view of an infusion set made inaccordance with the prior art;

[0024]FIG. 2A shows a fragmented, side cross-sectional view of anapparatus and method for preventing free-flow through an infusion set inthe form of an occluder mounted in an infusion set with the occluder andinfusion set in a closed configuration;

[0025]FIG. 2B shows a fragmented, side cross-sectional view of similarto that of FIG. 2A, wherein the occluder and infusion set are in an openconfiguration;

[0026]FIG. 2C shows a fragmented, side cross-sectional view of analternate occluder/infusion set configuration made in accordance withthe principles of the present invention;

[0027]FIG. 3A shows a fragmented, side cross-sectional view of analternate apparatus and method for preventing free-flow through aninfusion set in accordance with the principles of the present invention;

[0028]FIG. 3B shows a fragmented, cross-sectional view of an alternateoccluder embodiment, with the occluder and infusion set being disposedin a closed configuration;

[0029]FIG. 3C shows a cross-sectional view of the occluder embodiment ofFIG. 3A with the occluder and infusion set being disposed in an openconfiguration;

[0030]FIG. 3D shows a fragmented, side cross-sectional view of anotherembodiment of an occluder and infusion set made in accordance with theprinciples of the present invention;

[0031]FIG. 3E shows a fragmented, side cross-sectional view of still yetanother embodiment of an occluder and infusion set made in accordancewith the principles of the present invention;

[0032]FIG. 4A shows fragmented, side cross-sectional view of anotherembodiment of an occluder and infusion set with the occluder in anclosed configuration;

[0033]FIG. 4B shows a cross-sectional view of the embodiment of FIG. 4Ain an open configuration;

[0034]FIG. 5A shows fragmented side cross-sectional view of an occluderand infusion set made in accordance with one aspect of the presentinvention with the occluder and infusion set being in a closed position;

[0035]FIG. 5B shows a cross-sectional view taken along plane A-A of FIG.5A;

[0036]FIG. 5C shows a fragmented, side cross-sectional view of aninfusion set with an occluder disposed therein, with the infusion setbeing mounted in a control mechanism to maintain the infusion set andoccluder in an open configuration;

[0037]FIG. 5D shows a cross-sectional view taken along the plane B-B ofFIG. 5C;

[0038]FIG. 5E shows a perspective view of a housing of a controlmechanism as may be used to hold the infusion set and occluder in anopen position as shown in FIG. 5D;

[0039]FIG. 6A shows a fragmented, side cross-sectional view of aninfusion set having an occluder formed therein in accordance with anaspect of the present invention;

[0040]FIG. 6B shows a view similar to that shown in FIG. 6A with theoccluder held in an open position.

[0041]FIG. 7 shows another configuration of an occluder made inaccordance with the principles of the present invention.

[0042]FIG. 8 shows yet another configuration of an occluder made inaccordance with the principles of the present invention;

[0043]FIG. 8A shows a cross-sectional view of another configuration ofan occluder in accordance with the present invention;

[0044]FIG. 8B shows a cross-sectional view of still yet anotherconfiguration of an occlude of the present invention;

[0045]FIG. 9 shows yet another aspect of the invention wherein theoccluder forms part of a liquid control valve.

[0046]FIG. 10 shows a perspective view of a clip for retrofittingexisting pumps of use with an occluder of the present invention;

[0047]FIG. 11 shows a side cross-sectional view of a pair of occludersand infusion line which form a pair of valves, and a force applicator toform a linear peristaltic pump;

[0048]FIG. 12A shows a front view of an enteral feeding pump of theprior art with an occluder in accordance with the present inventiondisposed therein; and

[0049]FIG. 12B shows a close-up, cross-sectional view of the occluder,infusion set and a portion of the pump to demonstrate opening of a fluidflow pathway around the occluder.

DETAILED DESCRIPTION

[0050] Reference will now be made to the drawings in which the variouselements of the present invention will be given numeral designations andin which the invention will be discussed so as to enable one skilled inthe art to make and use the invention. It is to be understood that thefollowing description is only exemplary of the principles of the presentinvention, and should not be viewed as narrowing the pending claims.

[0051] Referring to FIG. 1, there is shown a perspective view of aninfusion set 10 and related structures in accordance with the teachingsof the prior art. Disposed at one end 10 a of the infusion set 10 is abag 14 for holding parenteral or enteral solutions. Typically, the bag14 is supported by a stand 18 which holds the bag approximately 6 feetoff the floor.

[0052] The opposing end 10 b of the infusion set 10 is connected to apatient (not shown) In a parenteral use, the end of the infusion set 10would have a needle attached thereto which extends into the patient'svenous system. In a enteral use, the end 10 b would typically have afitting which attached to a balloon catheter (not shown) mounted in astoma in the patient's stomach. The end may also be connected to anasoenteric feeding tube.

[0053] Solution flows under gravity from the upper end 10 a of theinfusion set 10 to the lower end 10 b. The pressure on the fluid is0.433 psi per foot. Thus, if the bag 14 is disposed five feet higherthan the patient, the pressure at the lower end 10 b of the infusion set10 is 2.165 psi. From the extreme height of 8 feet to the floor, thesolution in the infusion set 10 can reach approximately 3.5 psi.

[0054] To control the flow of solution through the infusion set 10, theinfusion set is typically mounted through a flow control portion of apump 22. The pump 22 selectively allows a metered amount of solution topass distally (downstream) from the pump. This can be accomplished inmultiple ways. For example, many enteral feeding pumps are peristalticpumps which have a rotor which engages the infusion set 10 with aplurality rollers. Each partial rotation of the rotor allows apredetermined dose to pass to the patient. By controlling the rate atwhich the rotor turns, the pump can provide highly accurate doses of thesolution.

[0055] Other pumps known in the art control solution flow through theinfusion set 10 by a plurality of fingers which engage the infusion set.By controlling the position and frequency of the engagement of thefingers against the infusion set 10, a highly accurate dose can beprovided to the patient.

[0056] While the pump 22 controls the solution flow through the infusionset 10 when the infusion set is properly loaded, failure to load theinfusion set properly in the pump quickly develops a free flow conditionin which the solution flows uncontrolled through the infusion set. Toprevent free flow, a clamp 26 is disposed along the infusion set 10.Typically, the clamp 26 is disposed above the pump 22. One common typeof clamp 26 is a roller clamp which allows some control over thepresence of flow and flow volume through the infusion set 10. Otherclamps simply provide on/off control.

[0057] While the infusion set 22 should be mounted in the pump 22 priorto or immediately after opening the clamp, this is not always done.There are many situations in a hospital or nursing home setting in whichthe nurse or physician is called away or otherwise distracted prior toproper placement of the infusion set 10. The result is that the solutionin the bag 18 flows uncontrolled into the patient.

[0058] In many situations, the free flow of the solution will cause noreal threat to the patient. In some situations, however, free flow cancause serious injury or even death to the patient. For example, acritically ill patient may suffer severe shock if a large amount ofsolution were to suddenly flow into his or her body. Likewise, a patientreceiving heavily medicated solution may be seriously injured if asolution that was designed to be delivered over a number of hours weredelivered in a few minutes.

[0059] To resolve such concerns, pinch clips may be disposed on theinfusion set 10. The pinch clip automatically closes the infusion setunless it is properly mounted in the infusion set 10. An example of sucha pinch clip is disclosed in U.S. Pat. No. 5,810,323.

[0060] While such occluders are a significant advantage over thepossibility of free flow, they are relatively expensive to make. Whilesuch an occluder may only cost ten to twenty cents, using a new occluderwith every infusion set adds a proportionally significant amount to thecost of an infusion set. Thus, there is a need to find an apparatus andmethod for preventing free flow in an infusion set which is reliable andwhich is less expensive than the prior art.

[0061] Turning now to FIG. 2A, there is shown a fragmented,cross-sectional of an infusion set, generally indicated at 100, with astop or occluder 104 disposed therein. The infusion set 100 is formed byan elongate tube 108 made of a flexible, resilient material such assilicone rubber, latex, polyurethane, neoprene or numerous similarmedical grade materials. (In light of the present disclosure, thoseskilled in the art will appreciate that the present invention may beused in nonmedical contexts as well. In such situations, the tube madebe made of materials which are not medical grade.)

[0062] The occluder 104 has an exterior diameter which is slightlylarger than the interior diameter of the tube forming the infusion set100. This causes a portion 108 a of the tube to stretch slightly as ispasses over the occluder 104.

[0063] The occluder 104 prevents flow through the infusion set 100 basedon gravity. Thus, the size of the occluder 104 will depend on thematerial used to form the infusion set. In a presently preferredembodiment, the infusion set 100 is formed from a tube made of siliconerubber. The tube has a wall thickness of approximately 0.038 inches andan inner diameter of approximately 0.130 inches. The occluder 104 ispreferably formed out of a plastic (e.g. acrylic (PMMA), polycarbonate,etc.) or a stainless steel ball bearing having an outer diameter of0.141 inches.

[0064] Because the occluder 104 is larger than the interior diameter ofthe infusion set 100, solution which is under only the force of gravitywill back-up behind the occluder and not pass. To prevent the occluder104 from gradually working its way downstream, a projection 112 can beformed in the infusion set 100 or, as explained in detail below, theoccluder may be fastened to a connector or some other stationarystructure.

[0065] Because the infusion set 100 is formed by an elongate, resilienttube 108, increases in pressure will cause the interior diameter of thetube to expand. When the tube 108 expands sufficiently, the portion 108a of the tube which passes over the occluder 104 allows the solution toflow around the occluder and into the distal part 100 b of the infusionset 100 as shown in FIG. 2B.

[0066] Preferably, the occluder 104 and infusion set 100 are selected sothat up to 4 psi can be maintained upstream of the occluder, i.e. in theproximal portion of the infusion set, before the portion 108 a of theelongate tube 108 extending over the occluder will expand sufficientlyto allow any clinically significant amount of solution to pass.

[0067] While solution hanging in the bag 18 may develop 2 to 3 psi dueto gravity, it will not have enough pressure to pass by the occluder 104without application of some external force. In contrast, an enteralfeeding pump or other type of pump will typically generate between 5 and10 psi. When the solution is pressurized to 5 to 10 psi by the pump, thesolution is under sufficient pressure to go around the occluder 104 fordelivery to the patient. In other words, if the infusion set 100 is notproperly mounted in the pump so that the pump will generate a higherpressure in the proximal part 100 a of the infusion set, the occluder104 inhibits flow to the patient. Thus, there can be no free flow whileaccommodating flow of solution to the patient when the infusion set 100is properly mounted in the pump.

[0068] Turning now to FIG. 2C, there is shown a fragmented, sidecross-sectional view of an alternate configuration of an infusion set,generally indicated at 130, and the occluder 104. As with the previousembodiment, the occluder 130 is formed by a small sphere, typicallyformed of a biologically inert plastic or stainless steel. The infusionset 130 is formed of a first tube 134 and a second tube 138. The firsttube 134 is formed of a resilient polymer or silicone so that the tubemay expand with pressure. The second tube 138 is typically slightlysmaller than the first tube 134 so that the distal end 134 a of thefirst tube can be attached to the exterior of the proximal end 138 a ofthe second tube.

[0069] To ensure that the occluder 104 does not advance distally intothe second tube 138, the second tube 138 is preferably formed from amaterial which is semi-resilient or nonresilient and therefore will notaccommodate advancement of the occluder 104. To prevent the proximal end138 a of the second tube 138 from forming a seal with the occluder 104,the proximal end preferably has one or more indentations 142 or contoursformed therein. The indentations 142 or contours ensure that liquid willbe able to flow around the occluder 104 even if the occluder is pressedfirmly against the proximal end 138 a of the second tube 138.

[0070] When pressures less than about 4 psi are disposed proximally fromthe occluder 104, the first tube 134 engages the occluder and preventsliquid from flowing down stream. Once the pressure on the proximal sideof the occluder 104 exceeds approximately 4 psi, the distal end 134 a ofthe first tube 134 distends and allows liquid to flow by in the mannerdemonstrated by arrows 146. Once the pressure subsides, the first tube134 returns to its original size and liquid flow terminates until thepressure again is raised above the threshold.

[0071] In use, the infusion set 130 and occluder 104 prevent free flowunless the infusion set is placed in engagement with a pump that cangenerate sufficient psi to compel flow around the occluder. Once pastthe occluder 104, the pressure of the liquid quickly falls and there isno danger to the patient.

[0072] Turning now to FIG. 3A, there is shown a fragmented,cross-sectional view of another embodiment of principle of the presentinvention. An infusion set 160 has a proximal portion 160 a and a distalportion 160 b. Disposed between the proximal portion 160 a and thedistal portion 160 b is an occluder or stop 164. The stop 164 isdisposed in the infusion set 160 to selectively prevent flow from theproximal portion 160 a to the distal portion 160 b.

[0073] The stop 164 includes a proximal end 164 a and a distal end 164b. Beginning at the proximal end 164 is a channel 170. As shown in FIG.3A, the channel has a proximal portion 170 a and two distal portions 170b which are in fluid communication with the proximal portion. While theproximal portion 170 a is disposed in continuous communication with theinterior of the proximal portion 160 a, each of the distal portions 170b of the stop 164 are typically disposed in communication with thesidewall of the infusion set 160. The sidewall of the infusion set 160normally prevents fluid flow out of the distal portions 170 b of thechannel 170.

[0074] Preferably the sidewall will have sufficient resistance toexpansion that a pressure of about 4 psi could be placed in the channel170 without causing the infusion set 160 to radially distend. Thus, ifthe pressure in the proximal portion 160 a of the infusion set 160 isbelow about 4 psi, the liquid will not flow through the stop 164.

[0075] As shown in FIG. 3A, the stop 164 is relatively long. To maintainitself in place, the stop 164 frictionally engages the sidewall definingthe infusion set 160. By providing a stop 164 which is long, greatersurface area is provided to engage the sidewall and prevent the stop 164from being slowly moved downstream.

[0076] Turning now to FIG. 3B, there is shown a fragmented, sidecross-sectional view of an infusion set, generally indicated at 180. Theinfusion set 180 includes a proximal (upstream) end 180 a and a distal(downstream) end 180 b which are separated by an occluder or stop 184.The stop 184 is similar to the stop 164 shown in FIG. 3A in that it hasa channel 190 with a proximal portion 190 a and a pair of distalportions 190 b.

[0077] Rather than relying on an elongate body and frictional engagementwith the sidewall of the infusion set 180, the stop 184 has at least oneprojection 194 which extends outwardly from the stop to engage thesidewall of the infusion set and prevent advancement. Preferably, theprojection 194 is formed by an annular projection, or a plurality ofspaced projections extending radially outwardly from the stop 184.

[0078] Turning now to FIG. 3C, there is shown a cross-sectional view ofthe infusion set 180 and stop 184 of FIG. 3B. As the pressure in theproximal portion 180 a of the infusion set 180 increases to greater thanabout 4 psi, the infusion set will distend radially. This allows liquidcontained in the proximal portion 180 a of the infusion set 180 to flowinto the proximal portion 190 a of the channel 190, out the distalportions 190 b of the channel and into the distal portion 180 b of theinfusion set. Once the pressure drops below about 4 psi, the infusionset 180 will retract and the flow in the channel 190 will be terminatedas the sidewall of the infusion set covers the distal portions 190 b ofthe channel 190.

[0079] In such a manner, the embodiments shown in FIGS. 3A through 3Cprevent free flow by preventing liquid flow under 4 psi. Once theinfusion set 180 is properly mounted in the pump, the increased pressurecreated by rotation of the rotor (or other pressure source) overcomesthe restriction to flow imposed by the stop 184. When combined with thecontrol provided by the various types of infusion pumps, the occluder orstop 164 or 184 enables a predetermined amount of liquid to flow throughinfusion set 160 or 180 while preventing the dangers of free flowconditions.

[0080]FIG. 3D shows a side cross-sectional view of yet anotherembodiment of an infusion set, generally indicated at 200, having anoccluder or stop 204 disposed therein. The infusion set 200 includes aproximal portion formed by a first tube 208 and a distal portion formedby a second tube 212. The proximal end 212 a of the second tube 212 ismounted about the exterior of the distal end 208 a of the first tube208.

[0081] Disposed at the distal end 208 a of the first tube 208 and theproximal end 212 a of the second tube 212 is the stop 204. The stop 204has a channel 216 extending from a proximal end 204 of the stop to aradially lateral position adjacent the distal end 204 b of the stop.Thus, the channel is in fluid communication with liquid in the firsttube 208, but is normally isolated from the interior of the second tube212.

[0082] When pressures in the first tube exceed about 4 psi, the proximalend 212 a of the second tube 212 radially expands, thereby opening thedistal end of the channel 216 and allowing liquid to flow into thedistal portion of the infusion set formed by the second tube 212.

[0083] By positioning the stop 204 at the ends of two tube segments, thestop can be adhesively attached to either of the tubes to prevent distalmovement of the stop. This can be accomplished without interfering withthe ability of the stop to prevent flow below about 4 psi, whileallowing pressures above about 4 psi cause liquid to pass through theinfusion set.

[0084] While the embodiments of FIGS. 3A through 3D show embodiments inwhich the proximal end of the channel is in continuous communicationwith the upstream flow and the distal end of the channel is normallyclosed, the stop 164, 184 or 204 could be rotated so that the proximalor upstream portion of the channel is normally closed by the sidewall ofthe infusion set 160, 180 or 200 and the distal portion of the channelis always in communication with the distal portion of the infusion set.

[0085]FIG. 3E shows yet another embodiment of an infusion set, generallyindicated at 230, and an occluder 234. The occluder 234 is disposed inthe infusion set 230 so as to divide the infusion set 230 into aproximal, upstream portion 230 a and a distal, downstream portion 230 b.

[0086] The occluder 234 has a channel 238 which extends from a proximalend 234 a of the occluder to the distal end 238 b so as to form apassageway through which an infusion liquid, such as enteral feedingsolution, may pass. A wall 242 is disposed along the channel 238 toselectively prevent flow through the channel. In accordance with theprinciples of the present invention, the wall 242 is pivotably attachedto the occluder 234 in such a manner that the wall will not move toallow liquid flow through the channel until the proximal, upstreampressure exceeds 4 psi. (While described as requiring a thresholdupstream pressure, in light of the present disclosure those skilled inthe art will appreciate that the wall will move based on a pressuredifferential between the two proximal and distal portions of theinfusion set. Thus, the same effect could be generated by developing avacuum downstream from the occluder 234).

[0087] Once the desired pressure threshold has been reached, the wall242 will pivot and open the channel 238 to flow. Once the pressuredrops, the wall 242 will pivot closed in accordance with one method ofuse. In accordance with another method of use, however, the wall 242 canhave a score 246 formed therein. The wall 242 is designed to remainoccluding the infusion set 230 until the pressure threshold is exceeded.Once deflected out of the way, the wall may not return to its originalposition even after the pressure drop. Because the pressure increasenecessary to move the wall 242 is generated by the pump (not shown), theinfusion set 230 must have been properly loaded in the pump for the wallto open. When the infusion set 230 is properly loaded in the pump, thepump will prevent free flow. Thus, if the infusion set 230 is properlyloaded in the pump, the occluder does not need to continue to preventfree flow.

[0088] Turning now to FIGS. 4A and 4B, there are shown fragmented, sidecross-sectional views of yet another embodiment of the presentinvention. An infusion set, generally indicated at 250 has an occluder254 in the form of a duckbill valve formed therein to divide theinfusion set 250 into a proximal, upstream portion 250 a and a distal,downstream portion 250 b. The occluder 254 is formed of two vanes 258 aand 258 b which are biased into engagement with one another.

[0089] When the pressure in the proximal portion 250 a of the infusionset 250 is less than about 4 psi, the biasing of the vanes 258 a and 258b keep them in contact as shown in FIG. 4A. Once the pressure in theproximal portion 250 a exceeds about 4 psi, the pressure forces thevalves 258 a and 258 b away from each other, thereby allowing aninfusion liquid to flow through the occluder 254 and into the distalportion 250 b of the infusion set 250 as shown in FIG. 4B. In order forthe occluder 254 to work in such a manner, it is preferable for thevanes 258 a and 258 b to extend distally as they engage one another.However, the occluder 254 could be made so that the vanes extendproximally and then buckle once the threshold pressure has been passed.

[0090] The occluder 254 is shown as being molded integrally with theinfusion set 250. Such a configuration prevents any concern as towhether the occluder 254 may move during use. However, it is feasible toalso form such an occluder 254 as a separate unit and then position itwithin the infusion set 250. The occluder 254 could be held in placewith adhesives or merely a friction fit.

[0091] Turning now to FIG. 5A there is shown a fragmented, sidecross-sectional view of an infusion set, generally indicated at 300,with an occluder 304 disposed therein. Similar to the embodiment shownin FIG. 2A, the infusion set 300 is made of conventional silicone tubingor some other resilient or semi-resilient material, such as latex,polyurethane, etc.

[0092]FIG. 5B shows a cross-sectional view of the infusion set 300 andoccluder 304 taken along the plane A-A in FIG. 5A. As shown, the tubedefining the infusion set 300 forms a seal around the occluder 304 andprevents liquid from passing between the occluder and the tube formingthe infusion set.

[0093] Turning now to FIG. 5C, there is shown a side cross-sectionalview of the infusion set 300 and the occluder 304. Disposed behind theinfusion set 300 at the location of the occluder 304 is a wall 308. Aswill be discussed in additional detail below, the wall 308, the occluder304 and the infusion set 300 form a compression valve for selectivelyallowing liquid to flow through the infusion set.

[0094]FIG. 5D shows a cross-sectional view of the infusion set 300 andthe occluder 304 taken along the plane B-B in FIG. 5C. The infusion set300 and occluder 304 have been mounted between opposing walls 308 whichare spaced apart a distance slightly smaller than the outer diameter ofthe infusion set. As the infusion set 300 is placed between the opposingwalls 308, the sides of the tubing forming the infusion set arecompressed and held against the occluder 304. This compression alsocauses the top and bottom 300 a and 300 b portions of the tube to extendradially outwardly from the occluder 304, thereby opening a flow path312 above and below the occluder. The flow paths 312 enable liquid inthe infusion set 300 to flow around the occluder 304 and to flow to thepatient.

[0095] In the event that the infusion set 300 and occluder 304 arepulled out from between the opposing walls 308, the tube forming theinfusion set 300 will return to the position shown in FIGS. 5A and 5B,thereby terminating flow through the infusion set. Thus, theconfiguration shown in FIGS. 5A through 5D prevents free flow ofinfusion liquids through the infusion set 300 so long as the infusionset and occluder 304 are properly mounted between the walls 308 (or someanalogous engagement surfaces). The infusion set 300 and occluder 304are typically positioned between the walls 308 as the infusion set isbeing loaded into the pump (not shown). Once properly loaded, the pumpcontrols flow through the infusion set 300 and prevents free flow.

[0096] Turning now to FIG. 5E, there is shown a perspective view of ahousing of an enteral feeding pump, generally indicated at 330, made inaccordance with one aspect of the present invention. The housing 330includes a pair of channels 340 and 344 for holding a portion of aninfusion set tube, such as those discussed with respect to FIGS. 3Athrough 5D. In use, the tube is placed in one channel 340, wrapped abouta motor unit (not shown) which is placed in the opening 350, and thenpositioned in the second channel 344. If a conventional infusion set isnot properly wrapped about the motor unit (or properly installed inother types of pumps, and placed in the channels 340 and 344, afree-flow condition may develop. However, the present invention preventssuch a situation from developing.

[0097] As shown in FIG. 5E in broken lines, the infusion set 354 ismounted in the first and second channels 340 and 344. At least a portion340 a of the channel 340 is sufficiently narrow to form walls, similarto walls 308 in FIGS. 5A through 5D, which compress the sides of thetube forming the infusion set 354, thereby creating a flow path aroundthe occluder (not shown) in the infusion set. If desired, the entirelength of the walls 360 which form the channel 340 could be sufficientlyclose together to compress the infusion set 354 and thereby open flow.

[0098]FIG. 5E also shows a cover 370 which is connected to the housing330. The cover 370 is pivotable with respect to the housing 330 andincludes a catch 374 which engages a groove 380 on the housing. When thecover 370 is closed and the catch 374 engaged in the groove 380, theinfusion set 354 is securely held in the housing 330 and it is unlikelythat the infusion set may be pulled from the pump.

[0099] Rather than having the walls 360 of the channel 344 compress thesides of the infusion set 354 to form a compression valve with the sidesof the infusion set 354, a projection 384 can be mounted on the cover370 so that it is in alignment with the infusion set. When the covercloses, the projection 384 applies a downward force on the infusion set354 thereby forming an open compression valve with the flow channelsbeing disposed in horizontal alignment, rather than vertical alignmentas shown in FIG. 5D. Thus, liquid flowing through the infusion set 354passes around the sides of the occluder, as opposed to above and belowthe occluder.

[0100] It will be appreciated in light of the present disclosure, thatwhen a projection is used to engage the occluder, the occluder need notbe held in a channel. Rather, the infusion set 354 must only be engagedon generally opposing sides so as to open at least one flow path aroundthe occluder, or sufficient pressure must be exerted to cause theinfusion set to expand and open a flow path.

[0101] As long as the catch 374 on the cover 370 engages the groove 380on the housing 330, or the projection 384 is maintained in engagementwith the infusion set 354 at the location of the occluder, thecompression valve will remain open. If the cover 370 is opened, theforce holding the compression valve open is gone and the infusion set354 will retract into the closed position shown in FIGS. 5A and 5B,thereby preventing free flow through the infusion set 354.

[0102] Turning now to FIGS. 6A and 6B, there is shown yet anotherembodiment of the present invention. The infusion set, generallyindicated at 400, has an occluder 404 disposed therein. The occluder 404may be molded in the infusion set 400, or may be constructed separatelyand inserted.

[0103] The occluder 404 is formed by a first vane 408 a and second vane408 b which form a duck-bill valve. The vanes 408 a and 408 b aredisposed so that they extend proximally (i.e. upstream). As shown inFIG. 6A, the vanes 408 a and 408 b normally engage one other to occludeflow from a proximal portion 400 a of the infusion set 400 to a distalportion 400 b of the infusion set.

[0104] When pressure is applied to the tubing which forms the infusionset 400, the vanes 408 a and 408 b move away from each othersufficiently to allow fluid flow through the infusion set. Thus, in FIG.6, a compression valve is formed by sliding the infusion set 400 betweentwo walls 412 of engagement surfaces so that the vanes 408 a and 408 bare held apart, or by forcefully engaging the infusion set with aprojection or other structure associated with a door, etc. As long asthe infusion set 400 remains between the walls 412, projections, etc.,fluid flow is enabled. If the portion of the infusion set 400 whichcontains the occluder 404 is pulled from the walls 412 or projections,the occluder will return to the closed position wherein it prevents freeflow.

[0105] Preferably, the infusion set 400 and occluder 404 will be used ina housing, such as that shown in FIG. 5E. When the infusion set 400 ismounted in a channel defined by restricting sidewalls or when a coverwith an aligned projection is closed, flow is enabled through theinfusion set. If the infusion set 400 is pulled out of the housing, theoccluder 404 will automatically close—thereby preventing free flowthrough the infusion set.

[0106] The various embodiments disclosed in accordance with the presentinvention provide a marked improvement over clamps and other types ofexternal occluders which are commonly used to control fluid flow. Theembodiments provide assurance against free flow, are generally easier tohandle and are much more cost effective than the external occluders ofthe prior art.

[0107] In addition to being usable with housings and other fixedstructures which cause the valve to open, the majority of configurationsdiscussed above can also be manually opened by simply squeezing theinfusion set adjacent the occluder to open a pathway around theoccluder. The availability to manually open the occluder/infusion set isdesirable, as it facilitates priming of the infusion set with the liquidbeing infused. Unlike many of the occluders of the prior art however,simply releasing the infusion set adjacent the occluder is all that isrequired to terminate flow.

[0108] Turning now to FIG. 7, there is shown another configuration of aninfusion set, generally indicated at 400, and an occluder, 404 made inaccordance with the principles of the present invention. The infusionset 400 is formed by an elongate tube 108 made of a flexible, resilientmaterial such as silicone rubber, latex , polyurethane, neoprene ornumerous similar materials. Typically, the elongate tube has an innerdiameter of approximately 0.130 inches.

[0109] The occluder 404 has an exterior diameter which is slightlylarger than the interior diameter of the tube forming the infusion set400, typically about 0.141 inches. This causes a portion 408 a of thetube to stretch slightly as is passes over the occluder 404.

[0110] The occluder 404 prevents flow through the infusion set 400 basedon gravity. Thus, the exact size of the occluder 404 will depend on thematerial used to form the infusion set 400. In a presently preferredembodiment, the infusion set 400 is formed from a tube made of siliconerubber, and the occluder 404 is formed from a plastic (e.g. acrylic(PMMA), polycarbonate, etc.) cylinder having an outer diameter of 0.141inches and a length of about 0.282 inches.

[0111] Because the occluder 404 is larger than the interior diameter ofthe infusion set 400, solution which is under only the force of gravitywill back-up behind the occluder and not pass. Once sufficient pressureis present—e.g. pressure produced by a pump—the walls of the infusionset will expand to allow fluid flow past the occluder 400 as discussedwith respect to FIG. 2A, etc.

[0112] While the embodiment shown in FIG. 2A is spherical and theembodiment shown in FIG. 7 is cylindrical, those skilled in the art willappreciate that numerous other embodiments could be used. For example,the dashed line 412 illustrates an occluder which is bullet shaped.Occluders can also be egg shaped, or any other shape which provides astop to fluid flow until a predetermined pressure threshold has beenreached. It will also be appreciated that the occluder 404 need not havea consistent diameter. By having a portion of the occluder 404 extendradially a greater distance than other parts, a portion of the occluderwill always engage the wall of the infusion set 400, thereby reducingthe ability of the occluder to move within the infusion set.

[0113] Turning now to FIG. 8, there is shown still another configurationof an infusion set 420 and occluder 424 made in accordance with theprinciples of the present invention. The infusion set 420 is formed froman elongate tube 428 which has a first portion 432 and a second portion436 which are connected together by a connector 440. The occluder 424 isattached to the connector 440 by a tether 442 to prevent the occluderfrom advancing along the second portion 436 of the elongate tube 428.

[0114] When sufficient pressure is present in a proximal, upstreamportion 428 a of the elongate tube 428, the second portion 432 willexpand sufficiently to allow fluid flow past the occluder 424 and intothe distal, downstream portion 428 b of the infusion set 420. Oneadvantage of using the connector is that the first portion 428 a of theelongate tube 428 need not be formed of a material which is resilient,or may use a material which does not expand or contract consistently. Inother words, less expensive tubing materials may be used for most of theinfusion set 420 without interfering with the interaction between theinfusion set and the occluder 424.

[0115] While shown in FIG. 8 as being generally spherical, it should beappreciated that, in accordance with the present invention, the occluder424 could be a variety of shapes. Additionally, the a single tether 442or a plurality of tethers could be used to hold the occluder 424 to theconnector 440.

[0116]FIG. 8A shows a cross-sectional view of another configuration ofan infusion set 420, and an occluder 444. Unlike the spherical occluder424 of FIG. 8, the occluder 444 of FIG. 8A is disk shaped. To preventthe occluder 444 from rotating in response to fluid pressure andinadvertently opening a fluid flow path, a plurality of tethers 442 areused to secure the disk to the connector 440.

[0117] When pressure in the infusion set 420 is sufficient, the tube 428will expand and allow fluid flow past the occluder 444. Once thepressure drops below a predetermined threshold, the tube 428 will againengage the occluder 444 and terminate flow.

[0118]FIG. 8B shows a cross-sectional view of still yet anotherconfiguration of an occluder, 446, made in accordance with theprinciples of the present invention. The infusion set 420 and relatedportions are the same as in FIGS. 8 and 8A and are numbered accordingly.

[0119] The connector 440 is attached by one or more tethers 442 to theoccluder 446 to prevent the occluder from moving down stream. Thetethers 442 can also be used to keep the occluder 446 in a desiredorientation. When sufficient pressure is present, the tube 436 expandsto allow fluid flow past the occluder 446.

[0120]FIG. 9 shows yet another aspect of the invention wherein theinfusion set 450 and occluder 454 forms part of a liquid control valve,generally indicated at 460. In accordance with the embodiments discussedabove, and particularly the discussion surrounding 5A through 5E, theoccluder 454 normally prevents fluid flow through the infusion set.However, squeezing the infusion set on an opposing sides of the infusionset sidewall 450 a caused other portions of the sidewall to extend awayfrom the occluder 454—as demonstrated in FIGS. 5C and 5D.

[0121] Disposed adjacent to the infusion set 450 and occluder 454 are apair of engagement members 464 which are in communication with anactuator 468, such as a motor. The communication can be electronic,mechanical or pneumatic, so long as the actuator 468 is able to controlmovement of one or more of the engagement members 464.

[0122] When the engagement members are actuated, they apply and inwardforce to the infusion set 450 at the location of the occluder 454 toopen a passage way around the occluder and thereby enable fluid flowthrough the infusion set. When the engagement members 464 are adjustedto no longer apply sufficient force to the infusion set 450, theinfusion set again surrounds the occluder 454 and prevents fluid flow.

[0123] By selectively actuating the engagement members 464, the infusionset 450 and occluder 454 a valve is formed for controlling fluid flow.By applying a pressure sensor or other type of sensor, the valve can beused to regulate flow and flow through the valve can be determined.

[0124] Turning now to FIG. 10, there is shown a perspective view of aclip, generally indicated at 480, for opening flow between an occluderand infusion set. Those skilled in the art will appreciate that thereare a number of enteral and parenteral pumps in the market which usevarious types of occluders which suffer from the problems identified inthe background section. To eliminate these concerns, the clip 480 isconfigured for retrofitting an existing pump for use with anoccluder/infusion set made in accordance with the principles of thepresent invention. (Of course, with some existing pumps, the occluderand infusion set may be configured to nest in the pump in such a mannerthat retrofitting is not necessary.)

[0125] The clip 480 includes a base 484 which is provided for attachmentto the housing of a conventional fluid pump. Typically, the base 484will have an adhesive disposed thereon. If desired, the adhesive may beselected from removable adhesives, such as those known to those skilledin the art, so that the clip 480 can be removed from the pump when aninfusion set containing an occluder (such as that represented by thedashed lines 488) is not being used with the pump.

[0126] Extending from the base 484 is a fitting 490 having channel 492formed therein. The channel 492 is preferably formed with an open endand extends into the clip 480. As the infusion set, represented inshadow at 488, is inserted into the channel 492, walls 494 defining thechannel compress the infusion set 488 against the occluder (shown asdashed lines 498) to open a pair of flow channels between the occluderand the infusion set as shown in FIGS. 5A through 5D.

[0127] As long as the infusion set 488 and occluder 498 remain securelyheld between the walls 494 defining the channel 492, fluid flow isenabled between the occluder and the infusion set. If the infusion set488 is pulled from the channel 492 or is never properly placed in thechannel, flow through the infusion set is prevented. Thus, the risk offree flow developing within the system is significantly reduced. Ofcourse, the risk of free flow can virtually be eliminated by placing theclip 480 on the pump in such a manner that the infusion set 488 must beproperly loaded in the pump in order to fit within the channel 492.

[0128]FIG. 11 shows a side cross-sectional view of yet anotherembodiment of the present invention which forms an in-line pump,generally indicated at 500. As shown in FIG. 11, a pair of occluders 504and 508 are disposed in an infusion line 512. Each of the occluders 504and 508 is disposed adjacent an actuator 514 and 518, respectively. Theactuators 514 and 518 are configured to selectively apply pressure tothe infusion line 512 to selectively open flow channels between theinfusion line and the occluder 504 or 508 with which each is associated.

[0129] In use, liquid in the infusion line 512 will be held in aproximal portion 512 a which is upstream from the first occluder 504.The first occluder 504 prevents the liquid from flowing down streamuntil a drive mechanism 522 causes the first actuator 514 to apply forceto the infusion line 512 adjacent the first occluder. Applying force tothe infusion line 512 causes a channel to open between the firstoccluder 504 and the infusion line, thereby allowing fluid flow into amiddle portion 512 b of the infusion line.

[0130] Once the middle portion 512 b of the infusion line 512 has hadadequate time to fill with liquid, the actuator 514 is adjusted so thatit no longer applies sufficient force to the infusion line to enablefluid flow around the occluder 504. The liquid in the middle portion 512b of the infusion line 512 is then isolated from the liquid in theproximal portion 512 a.

[0131] The liquid in the middle portion 512 b of the infusion line 512is prevented from flowing distally or downstream by the second occluder508 which defines the distal end of the middle portion. However, oncethe drive mechanism 522 is actuated to move the actuator 518 intoforceful contact with the infusion line 512 adjacent the occluder 508,one or more channels are formed between the occluder and the infusionline. The channel(s) opened by the actuator 518 squeezing the infusionline 512 form a flow path allowing the liquid contained in the middleportion 512 b to flow into a distal, downstream portion 512 c. Since nooccluder or other stop is typically disposed distally from the secondoccluder 508, the liquid flowing into the distal portion 512 c isdelivered to the patient.

[0132] By selectively controlling the application of force by the firstactuator 514 on the infusion line 512 and first occluder 504 and theapplication of force by the second actuator on the infusion line andsecond occluder 508, a valve, generally indicated at 526, is formedwhich permits a predetermined amount of flow to pass with each series ofactuations.

[0133] In a more preferred embodiment, the valve also includes a forceapplicator 530, such as a plunger, roller or similar device, disposed incommunication with the middle portion 512 b of the infusion line 512.The force applicator 530 applies a compressive force to the middleportion 512 b of the infusion line 512 to force the liquid contained inthe middle portion 512 b to flow into the distal portion 512 c of theinfusion line 512 and on to the patient. The force applicator 530ensures that liquid will not simply remain in the middle portion 512 bwhen the second actuator 518 causes a flow path to be formed between thesecond occluder 508 and the infusion line 512.

[0134] While applying a compressive force to the middle portion 512 b ofthe infusion line 512 helps to force the liquid in the middle portion toflow downstream, it also serves to assist flow into the middle portion.Once a compressive force is no longer applied to the middle portion 512b, the resilient material forming the infusion line will attempt toreturn to its original, tubular configuration. By closing the flow pathbetween the second occluder 508 and the infusion line 512 beforereleasing force applicator 530, a vacuum is formed within the middleportion 512 b. Once the actuator 514 opens a flow path between the firstoccluder 504 and the infusion line 512, the vacuum in the middle portion512 b will draw liquid into the middle portion 512 b as the infusionline returns to its original configuration.

[0135] In each cycle of the valve 526, the first actuator 514 will opena flow channel between the first occluder 504 and the infusion line 512to fill the middle portion 512 b with liquid. The first actuator 514will then allow the flow channel to close. The second actuator 518 willthen open a flow channel between the second actuator 508 and theinfusion line 512 and the force applicator 530 will apply pressure tothe infusion line forming the middle portion 512 b so that the liquid inthe middle portion will flow into the distal portion 512 c and to thepatient. The second actuator 518 will then allow the flow channelbetween the second occluder 508 and the infusion line 512 to close. Theprocess will then be repeated.

[0136] By controlling the interior diameter of the infusion line 512,the distance between the first occluder 504 and the second occluder 508,and the movement/size of the force applicator 530, one can obtain apredetermined amount of liquid flow with each cycling of the valve 526.By controlling the number of cycles in a predetermined period of time,the operator is able to provide a highly accurate rate of flow for thesolution passing through the valve 526. Furthermore, because a rotor isnot needed to control flow rate, the valve 526 can be used to make anin-line peristaltic pump which is significantly thinner thanconventional peristaltic pumps while maintaining the same accuracy.

[0137] While FIG. 11 shows two actuators, those skilled in the art willunderstand, in light of the present invention, that one of the occluderscould be configured to allow fluid flow responsive to force ifconfigured properly to prevent back flow. This could be achieved, forexample, by controlling the size of the occluders.

[0138] Turning now to FIG. 12A, there is shown a perspective view of apump, generally indicated at 600, which is designed to control fluidflow through an infusion set, generally indicated at 604, and into thepatient. The pump 600 includes a control panel 608 which has a pluralityof buttons 610 or other devices for controlling the actuation of thepump. The pump 600 operates to deliver a predetermined dose of enteralfeeding solution to a patient by rotation of a rotor 612.

[0139] The infusion set 604 is mounted on the pump so that a resilientportion 604 a of the infusion set wraps around the rotor 612. Eachrotation or partial rotation of the rotor 612 causes a predeterminedamount of enteral feeding solution to be advanced through the infusionset 604 and delivered to the patient.

[0140] In order to assure that the rotor 604 is providing the properamount of enteral feeding solution, a drip chamber 620 is formed alongthe infusion set. An optical sensor 624 is disposed in the enteralfeeding pump 600 and monitors the drip rate of the solution in the dripchamber 624. The drip rate of the solution is used to calculate anactual delivery rate of the solution.

[0141] As with the prior art, a portion 604 b of the infusion setdisposed distally from the rotor 612 is nested in a channel 630 in thepump housing 600. In accordance with the present invention, the portion604 b has an occluder 634 disposed therein. While the prior art simplyused the channel 630 to hold the infusion set 604 in contact with therotors, the inclusion of an occluder 634 provides an improved measure ofsafety.

[0142] In the prior art, if either the portion 604 b of the infusion set604 was not properly positioned in the channel 630, a free flowcondition could develop in which fluid flow through the infusion setwould be unchecked by the rotor 612. In the present invention, flowthrough the infusion set 604 is not permitted until the portion 604 bwith the occluder 634 is nested in the channel 630. If the portion 604 bof the infusion set 604 is not properly placed in the channel 630 or ispulled from the channel, the occluder 630 will prevent free flow throughthe infusion set.

[0143]FIG. 12B shows a close-up, cross-sectional view of the portion ofthe pump 600 having the channel 630 formed therein taken along the lineA-A. The channel 630 receives the infusion set 604 in such a manner thatit compresses the tube 642 against the occluder 634. This causes anotherportion of the tube 642 to extend away from the occlude 634 and therebyopen a fluid flow path between the inner wall of the tube and theoccluder.

[0144] As shown in FIG. 5D, compressing opposing sides of the infusionset can open fluid flow channels both above and below the occluder. InFIG. 12B, the tube 642 of the infusion set 604 is pressed against onehalf of the occlude 634, thereby forming a single fluid flow channel 646on the opposing side. If the portion 604 b of the infusion set 604containing the occluder 634 is pulled from the channel 630, the infusionset will engage the occluder prevent fluid flow.

[0145] Thus there is disclosed an improved apparatus and method forpreventing free flow in an infusion line. The apparatus and method canbe used with infusion control pumps, such as enteral feeding pumps or IVpumps, or as a replacement for such pumps. While the present disclosurediscloses embodiments which are currently preferred, those skilled inthe art will appreciate numerous modifications which can be made withoutdeparting from the scope and spirit of the present invention. Forexample, the relative size of the infusion set and occluder could bechanged by providing an occluder which shrinks sufficiently underpressure to create fluid flow passages. The appended claims are intendedto cover such modifications.

What is claimed is:
 1. An apparatus for preventing free flow through aninfusion set, the apparatus comprising: an infusion set formed offlexible tubing, the infusion set having a proximal portion and a distalportion; and an occluder disposed in the infusion set between theproximal portion and the distal portion for selectively preventing flowof liquid through the infusion set.
 2. The apparatus of claim 1, whereinthe infusion set comprises a resilient tubing, at least a portion ofwhich expands responsive to increases in pressure within the proximalportion of the infusion set.
 3. The apparatus of claim 2, wherein theoccluder comprises a sphere.
 4. The apparatus of claim 2, wherein theoccluder comprises a cylinder.
 5. The apparatus of claim 2, wherein theoccluder is bullet-shaped.
 6. The apparatus of claim 2, wherein theoccluder has a cross-section which is ellipsoidal.
 7. The apparatus ofclaim 2, wherein the occluder is disk-shaped.
 8. The apparatus of claim2, wherein the occluder is diamond-shaped.
 9. The apparatus of claim 2,wherein the occluder comprises a stop positioned within the tubing ofthe infusion set.
 10. The apparatus of claim 9 wherein the stop has achannel formed therein, the channel having a first end and a second end,and wherein one of the first and second ends is disposed in continuouscommunication with one of proximal and distal portions of the infusionset and wherein the other of the first and second ends is normallyclosed by the tubing of the infusion set.
 11. The apparatus of claim 10,wherein the tubing of the infusion set expands responsive to increasedpressure in the channel and opens the normally closed end of the channelto permit flow of liquid through the channel.
 12. The apparatus of claim9, wherein the stop has a channel and a wall disposed to normallysubstantially prevent flow of liquid through the channel, the wall beingresponsive to increases in pressure to allow liquid flow through thechannel when the pressure exceeds a desired threshold.
 13. The apparatusof claim 12, wherein the wall is resilient and returns to a flowprohibiting position when the pressure falls below the predeterminedthreshold.
 14. The apparatus of claim 12, wherein the wall is scored toremain open after the pressure has dropped below the predeterminedthreshold.
 15. The apparatus of claim 1, wherein the occluder comprisesat least one vane moveable between a first position and a secondposition responsive to a pressure differential between the proximalportion and the distal portion of the infusion set.
 16. The apparatus ofclaim 15, wherein the occluder comprises a duck bill valve.
 17. Theapparatus of claim 1, further comprising movement preventing means forpreventing the occluder from moving distally within the tubing of theinfusion set.
 18. The apparatus of claim 15, wherein the movementpreventing means comprises projections formed in the tubing of theinfusion set.
 19. The apparatus of claim 17, wherein the movementpreventing means comprises projections extending from the occluder. 20.The apparatus of claim 17, wherein the movement preventing meanscomprises a tether.
 21. The apparatus of claim 17, wherein the occluderis tethered to a fitting connecting two portions of the infusion linetogether.
 22. The apparatus of claim 1, wherein the tubing of theinfusion set and the occluder form a portion of a compression valvewherein applying pressure to the tubing of the infusion set enablesliquid flow past the occluder.
 23. The apparatus of claim 1, furthercomprising a plurality of engagement surfaces for contacting andcompressing the tubing of the infusion set to enable liquid flow pastthe occluder.
 24. The apparatus of claim 23, wherein the occluder has ashape selected from the group consisting of a spherical, cylindrical,ellipsoidal, bullet-shaped, disk-shaped and diamond-shaped and whereinthe engagement surfaces compress portions of the tubing of the infusionset against the occluder to form flow passages between the occluder andportions of the tubing not compressed by the engagement surfaces. 25.The apparatus of claim 23, wherein the occluder is a valve and whereinthe engagement surfaces compress a portion of the tubing of the infusionset to open the valve.
 26. The apparatus of claim 1, further comprisinga pump housing, the pump housing having at least one channel formedtherein for receiving a portion of the infusion set.
 27. The apparatusof claim 1, further comprising a pump housing having a plurality ofengagement surfaces for contacting and compressing the tubing of theinfusion set to enable liquid flow past the occluder when a portion ofthe infusion set containing the occluder is disposed within the channel.28. The apparatus of claim 1, further comprising a pump housing having acover attached to the housing for selectively holding the infusion setwithin the housing.
 29. The apparatus of claim 28, wherein the cover hasa projection disposed thereon, the projection being in alignment withthe infusion set such that closing the cover causes the projection toengage the infusion set and compress a portion of the infusion set tothereby enable flow of liquid past the occluder.
 30. The apparatus ofclaim 1, further comprising a second occluder disposed in the infusionset for dividing the infusion set into a proximal portion, a middleportion, and a distal portion, the middle portion being disposed betweenthe two occluders.
 31. The apparatus of claim 30, further comprising aforce actuator disposed in communication with the middle portion forselectively applying a compressive force to the middle portion.
 32. Anapparatus for selectively preventing free flow through an infusion set,the apparatus comprising: an infusion set comprising an elongate pieceof tubing having a proximal portion and a distal portion, the infusionset being formed from a resilient material which radially expandsresponsive to pressure within the tubing; and an occluder positionedwithin the tubing of the infusion set so as to divide the infusion setinto the proximal portion and the distal portion, the occluder beingconfigured to substantially eliminate flow of liquid from the proximalportion of the infusion set to the distal portion while pressure withinthe proximal portion remains below a predetermined threshold, whileallowing flow of liquid from the proximal portion to the distal portionwhen pressure in the proximal portion exceeds a predetermined threshold.33. The apparatus of claim 32, wherein the occluder is disposed withinthe tubing of the infusion set and wherein pressures in the proximalportion of the infusion set which exceed the predetermined thresholdcause the tubing of the infusion set to radially expand, therebyallowing fluid flow around the occluder.
 34. The apparatus of claim 33,wherein the occluder comprises a sphere.
 35. The apparatus of claim 33,wherein the occluder comprises a cylinder.
 36. The apparatus of claim33, wherein the occluder has a cross-sectional shape which isellipsoidal.
 37. The apparatus of claim 33, wherein the occluder isbullet-shaped.
 38. The apparatus of claim 33, wherein the occluder isdisk-shaped.
 39. The apparatus of claim 33, wherein the occluder isdiamond-shaped.
 40. The apparatus of claim 32, wherein the occluder isdisposed within the tubing, the occluder having a channel formedtherethrough for enabling fluid flow from the proximal portion to thedistal portion and means for preventing flow of liquid through thechannel when pressure in the proximal portion is less than thepredetermined pressure, while allowing flow of liquid through thechannel when pressure in the proximal portion exceeds the predeterminedpressure.
 41. The apparatus of claim 40, wherein the means forpreventing flow of liquid comprises a wall which closes the channel whenpressure within the proximal portion is less than the predeterminedpressure.
 42. The apparatus of claim 40, wherein the means forpreventing flow of liquid comprises a portion of tubing of the infusionset which prevents flow through the channel and into the distal portionwhen pressure in the proximal portion is less than the predeterminedpressure.
 43. The apparatus of claim 32, further comprising means forpreventing distal advancement of the occluder.
 44. The apparatus ofclaim 32, further comprising a plurality of engagement surfaces forcompressing portions of the tubing of the infusion set against theoccluder to open flow passages between the occluder and other portionsof the infusion set.
 45. An apparatus for selectively preventing freeflow through an infusion set, the apparatus comprising: an infusion setcomprising an elongate piece of tubing having a proximal portion and adistal portion; and an occluder positioned within the tubing of theinfusion set so as to divide the infusion set into the proximal portionand the distal portion, the occluder comprising a valve being configuredto substantially eliminate flow of fluid from the proximal portion ofthe infusion set to the distal portion while pressure within theproximal portion remains below a predetermined threshold, while allowingflow of fluid from the proximal portion to the distal portion whenpressure in the proximal portion exceeds a predetermined threshold. 46.The apparatus of claim 45, wherein the occluder comprises a least onevane which prevents flow from the proximal portion to the distal portionwhen pressure in the proximal portion is less than the predeterminedpressure.
 47. The apparatus of claim 46, wherein the occluder forms aduckbill valve.
 48. An apparatus for selectively preventing free flowthrough an infusion set, the apparatus comprising: an infusion setcomprising an elongate piece of tubing having a proximal portion and adistal portion, the infusion set being formed from a resilient materialwhich expands responsive to pressure within the tubing; an occluderpositioned within the tubing of the infusion set so as to divide theinfusion set into the proximal portion and the distal portion, theoccluder being configured to selectively prevent flow of liquid from theproximal portion of the infusion set to the distal portion; and meansfor applying force to the infusion set adjacent the occluder to therebyform a flow channel between the occluder and the infusion set to allowfluid flow past the occluder.
 49. The apparatus of claim 48, wherein themeans for applying a force comprises engagement surfaces.
 50. Theapparatus of claim 48, wherein the means for applying a force comprisesan actuator configured for selectively engaging the infusion set.
 51. Amethod for preventing free flow through an infusion set, the methodcomprising: selecting an infusion set having a proximal portion and adistal portion separated by an occluder disposed therein; filling theproximal portion with a fluid for administration to a patient; andpreventing the fluid from flowing into the distal portion of theinfusion set until a predetermined pressure differential exists betweenthe proximal portion and the distal portion.
 52. The method according toclaim 51, wherein the method comprises selecting an infusion set whichwill radially expand when the predetermined pressure differential isexceeded to allow liquid to flow into the distal end of the infusionset.
 53. The method according to claim 52, wherein the method comprisesselecting an infusion set having a sphere disposed therein to preventflow when the infusion set is not radially expanded.
 54. The methodaccording to claim 52, wherein the method comprises selecting aninfusion set having a stop with a channel formed therein disposed withinthe infusion set, and wherein flow through the channel is regulated byradial expansion of the infusion set.
 55. The method according to claim51, wherein the method comprises selecting an infusion set having aduckbill valve disposed therein.
 56. The method according to claim 52,wherein the method further comprises placing the infusion set in adevice that compresses at least a portion of the infusion set to allowflow to pass from the proximal portion to the distal portion past theoccluder.
 57. A method for preventing free flow through an infusion set,the method comprising: selecting an infusion set having an occluderdisposed therein so as to divide the infusion set into a proximalportion and a distal portion; filling the proximal portion with a fluidto be administered to a patient; preventing the liquid from flowing fromthe proximal portion to the distal portion until fluid flow into thedistal portion is desired; and opening flow to the distal portion of theinfusion set.
 58. The method according to claim 57, wherein the methodcomprises pressurizing the liquid in the proximal portion to at least apredetermined threshold to open flow past the occluder.
 59. The methodaccording to claim 58, wherein the method comprises pressurizing thefluid in the proximal portion to radially expand the infusion set andthereby allow flow of fluid past the occluder.
 60. The method accordingto claim 58, wherein the method comprises pressuring the fluid until thefluid opens a valve within the infusion set.
 61. The method according toclaim 57, wherein the method comprises compressing the infusion set toallow flow of fluid past the occluder.
 62. The method according to claim57, wherein the method comprises compressing the infusion set to open avalve formed by the occluder and infusion set.
 63. The method accordingto claim 57, wherein the method further comprises disposing a portion ofthe infusion set in a channel formed in a pump housing.
 64. The methodaccording to claim 64, wherein the method comprises forcefully nesting aportion of the infusion set in the pump housing to opens flow betweenthe occluder and the infusion set.
 65. The method according to claim 64,wherein the method further comprises holding the infusion set in thepump housing by closing a cover attached to the pump housing.
 66. Themethod according to claim 64, wherein the method further comprisesclosing a cover attached to the pump housing to compress the infusionset and open flow therethrough.
 67. The method according to claim 64,wherein the method comprises wrapping a portion of the infusion setaround a rotor.
 68. The method according to claim 67, wherein the methodfurther comprises nesting the occluder and infusion set into the channelto secure engagement between the infusion set and the rotor.
 69. Themethod according to claim 57, wherein the method further comprisesholding the infusion set in a pump housing by closing a cover attachedto the pump housing.
 70. The method according to claim 69, wherein themethod further comprises closing the cover to compress the infusion setand open flow therethrough.
 71. A valve for controlling fluid flow, thevalve comprising: an elongate flexible infusion line configured forcarrying liquids, the infusion line having a proximal portion, a middleportion, and a distal portion; a first occluder disposed in the infusionset for selectively preventing flow of liquid from the proximal portionto the middle portion; a second occluder disposed in the infusion setfor selectively preventing flow of liquid from the middle portion to thedistal portion; and a first actuator associated with the first occluderfor selectively applying force to the infusion line to enable fluid flowfrom the proximal portion to the middle portion past the first occluder.72. The valve according to claim 71, further comprising: a secondactuator associated with the second occluder for selectively applyingforce to the infusion line to enable fluid flow from the middle portionto the distal portion past the second occluder.
 73. The valve accordingto claim 72, further comprising a drive means for moving the firstactuator and the second actuator.
 74. The valve according to claim 71,wherein the infusion line is formed from a resilient material, andwherein application of force by the first actuator against the infusionline forms a flow channel between the infusion line and the firstoccluder.
 75. The valve according to claim 72, wherein the infusion lineis formed from a resilient material, and wherein application of force bythe second actuator against the infusion line forms a flow channelbetween the infusion line and the second occluder.
 76. The valveaccording to claim 71, further comprising a force actuator disposedadjacent the middle portion for applying force to the middle portion toforce fluid in the middle portion to flow into the distal portion.
 77. Amethod for controlling fluid flow through an infusion line, the methodcomprising: selecting an infusion line having a first occluder and asecond occluder disposed therein so as to divide the infusion line intoa proximal portion, a middle portion and a distal portion, the middleportion being between the first occluder and the second occluder;selectively applying force to the infusion line adjacent the firstoccluder to enable fluid flow from the proximal portion, past the firstoccluder and into the middle portion; and selectively applying force tothe infusion line adjacent the second occluder to enable fluid flow fromthe middle portion, past the second occluder and into the distalportion.
 78. The method according to claim 77, wherein the methodcomprises terminating fluid flow from the proximal portion into themiddle portion prior to enabling fluid flow from the middle portion intothe distal portion.
 79. The method according to claim 77, wherein themethod comprises compressing the middle portion to force fluid to flowfrom the middle portion into the distal portion.
 80. A method forretrofitting a pump for use with a infusion line having an occluderdisposed therein, the method comprising: selecting a pump; and attachingto the pump a clip having a channel formed therein which is configuredto receive an infusion line and occluder.
 81. The method according toclaim 80, wherein the method further comprises sliding an infusion lineinto the channel such that the channel applies a compressive force tothe infusion line to form a flow channel between the infusion line andthe occluder.